driver.hideKeyboard() will only work with AppiumDriver. I am using java-client-2.2.0.jar that contains this capability.
driver.hideKeyboard()
AppiumDriver
Best way is to use the back button.
driver.navigate().back(); // For older version of appium
Add these desired capabilities values if you want to disable the keyboard on your android selenium tests.
capabilities.setCapability("unicodeKeyboard", true);capabilities.setCapability("resetKeyboard", true);